U.N.-Arab League envoy Kofi Annan is "gravely concerned" by a step up in fighting by Syrian government forces and the opposition, his spokesman said on Monday.

Annan "is gravely concerned by the latest reports of violence coming out of Syria and the escalation of fighting by both government and opposition forces," said Ahmad Fawzi in a statement.

France said it would hold talks with Russia on its idea of an international Syria conference, as it urged the new head of the Syrian National Council to unite the opposition.

Paris congratulated Kurdish activist Abdel Basset Sayda on his naming as the SNC's new leader at the weekend, calling on him to work to bring the diverse regime opponents together.

Accused of the most barbaric massacres since the start of the revolt in Syria, the shabiha are feared militiamen and tools of a regime seeking to dissociate itself from atrocities, experts and activists say.

While there is no hard evidence of the involvement of these gunmen in the repression, United Nations officials have expressed "strong suspicions" about their role, notably in the Houla massacre that left 108 dead on May 25 and 26.

France said Monday it will hold talks with Russia on its idea of an international Syria conference including Iran and urged the new head of the Syrian National Council to unite the opposition.

"We will have new contacts with Russia this week on the subject," a ministry spokesman, Vincent Floreani, told a press conference.

Helicopter gunships on Monday fired on rebels in central and northwestern Syria in a bid to snuff out armed opposition as violence killed 103 people across the country, a watchdog and activists said.

The Local Coordination Committees, the main activist group spurring protests on the ground, said regime forces killed 89 people across the country, including women, children and rebels.

Syrian rebel army chief, Colonel Riyadh Asaad, denied in comments published Monday that Kuwaitis were fighting alongside his men against forces of President Bashar Assad's regime.

"Reports indicating the presence of Arab fighters (in Syria) are totally baseless," Asaad was quoted as saying by Kuwait's al-Watan newspaper.

Russian Foreign Minister Sergei Lavrov will visit Iran on Wednesday to discuss the upcoming Moscow talks on Tehran's nuclear program as well as the Syria crisis, his ministry said.

"The focus of attention... will be on the situation in the Middle East and North Africa, with the emphasis on the current transformation processes taking place in the Arab world and Syria," news agencies quoted a foreign ministry official as saying Monday.

Israel's deputy military chief has warned that Syria has the biggest chemical weapons stocks in the world and missiles and rockets that can reach any point in Israel.

Maj. Gen. Yair Naveh also said if Syria had the chance, it would "treat us the same way it treats its own people."

The national dialogue resumed its sessions on Monday “amid positive talks” with gatherers agreeing on committing to international resolutions and controlling Lebanon’s border.

The concluding statement said: “We reject the formation of a buffer zone with Syria and the use of Lebanon as an open ground for smuggling arms to Syria.”

The situation in Syria resembles that of Bosnia in the 1990s, British Foreign Secretary William Hague said Sunday.

He said Syria seemed on the edge of collapse into sectarian civil war, as he refused to rule out the option of military intervention.